The invention relates to X-ray apparatus, and more particularly relates to X-ray apparatus which is used during special purpose cardiac catheterization. In its most immediate sense, the invention relates to apparatus which is used during percutaneous transluminal coronary angioplasty (PTCA).
It has long been known that heart function can be impaired by stenotic deposits in the coronary arteries. Such deposits can become relatively large and block blood flow through the artery.
In PTCA, an inflatable catheter is introduced into the patient's circulatory system and guided to a stenosis (blockage) in the patient's heart. When the catheter is properly positioned, it is inflated to a greatly increased size and brought to bear against the stenosis. This causes the stenosis to break up into smaller pieces or to be flattened against the arterial wall, clearing the artery and thereby improving blood flow through it.
X-ray equipment has long been used to aid the PTCA procedure. Ideally, the equipment shows the radiologist or cardiologist where the catheter is actually located. (For the purposes of this disclosure, the difference between a radiologist and a cardiologist is unimportant. In the interest of brevity, the term "radiologist" will be used hereinafter, it being understood that this disclosure applies equally well to cardiologists.) This permits the radiologist to properly guide the catheter to the desired location without e.g. making wrong turns and guiding the catheter in the wrong direction at an arterial fork. Conventionally, as for example in the DIGITRON.RTM. unit sold by Siemens Medical Systems, Inc., a stored opacified image of the relevant portion of the patient's circulatory system (such an image shows the arterial structure and is called a roadmap) is either summed with a real-time fluoroscopic (colloquially, "fluoro") image which includes the catheter or displayed on a separate monitor. The resulting images can be used to guide the catheter to the proper location.
However, existing X-ray equipment suffers from two major disadvantages. First, it is not generally intended for use by the radiologist during the catheterization process and is not easily adapted for use under sterile conditions. This is because conventional equipment uses a keyboard or mouse as a major user interface and such an interface is impractical for a catheterization laboratory.
Second, and equally importantly, conventional X-ray equipment does not present information in such form as would be most useful for the radiologist. Under certain circumstances and in certain stages of the PTCA procedure, the radiologist wishes to see the roadmap of the patient's circulatory system, i.e. the diameter, direction etc. of the artery in which the catheter is being advanced, together with the real-time fluoro image of the catheter and nearby bones and organs. Under other circumstances and in other stages of the PTCA procedure, the radiologist is exclusively interested in the position of the catheter relative to other body structure (bones, organs, etc.) Roadmap information is then irrelevant and distracting.
As a result of such limitations, a PTCA procedure frequently lasts for two hours or more. This is disadvantageous; it is desirable to shorten the duration of any interventional operation. Additionally, since the catheter is in the heart and the patient may have heart distress and require open-heart surgery, an empty operating room is usually held ready until the PTCA procedure is completed. This is quite costly and quite wasteful of limited hospital resources.
It would be advantageous to provide apparatus which could be used by the radiologist during the PTCA procedure to reduce the duration of the PTCA procedure.
One object of the invention is to provide a device which is usable by a radiologist during a PTCA procedure.
Another object of the invention is to provide a device which allows the radiologist to adjust the image information presented to him during a PTCA procedure so as to match the information presented with the information desired.
A further object of the invention is to provide a device which is usable by a radiologist in the sterile conditions of a catheterization laboratory while the radiologist is standing at the patient's bedside.